UIAlertController的UIAlertView show（）行为 [英] UIAlertView show() behavior for UIAlertController

问题描述

在iOS的早期版本中，我能够在App Delegate中的UIAlertView上调用 show 。更具体地说， show 被调用：

In previous versions of iOS I was able to call show on a UIAlertView in the App Delegate. More specifically, show was called in:

func applicationDidBecomeActive(application: UIApplication)

由于 UIAlertView s忽视了视图在大多数情况下，无论用户在应用程序中的哪个位置，此解决方案都能正常工作。

Since UIAlertViews disregarded the view hierarchy in most cases, this solution worked no matter where the user was in the app.

随着 UIAlertController 这个问题变得有点棘手。 UIAlertController 现在是 UIViewController 的子类，需要像任何其他UIViewController一样呈现。虽然呈现UIAlertController从keyWindow的RootViewController的作品，它不是理想的解决方案。

With the introduction of UIAlertController this problem becomes a little trickier. UIAlertController is now a subclass of UIViewController and needs to be presented just like any other UIViewController. While presenting the UIAlertController from the keyWindow's rootViewController works, it's not the ideal solution.

有没有人对复制 [UIAlertView中查看] UIAlertController 的功能？有没有在遍历视图层次结构的情况下在应用程序上显示 UIAlertController 的方法？

Does anyone have any ideas on replicating [UIAlertView show] functionality for a UIAlertController? Any way to show the UIAlertController on app active without traversing the view hierarchy?

推荐答案

我找到了一个解决方案，我认为它比我之前发布的答案更优雅。我将复制并粘贴我发布的答案类似的问题。如果您只想查看代码，请点击我帖子底部的链接。

I figured out a solution that I believe to be more elegant than the answer I posted previously. I'll copy and paste the answer I posted to a similar question. Follow the link at the bottom of my post if you just want to see the code.

解决方案是使用额外的UIWindow。

The solution is to use an additional UIWindow.

当你想要显示你的UIAlertController时：

When you want to display your UIAlertController:

1. 让你的窗口成为关键和可见窗口（ window.makeKeyAndVisible（））


2. 只需使用普通的UIViewController实例作为新窗口的rootViewController。 （ window.rootViewController = UIViewController中（））


3. 呈现您窗口的RootViewController的你的UIAlertController

需要注意的一些事项：

• 必须强烈引用您的UIWindow。如果它没有被强烈引用，它将永远不会出现（因为它被释放）。我建议使用一个属性，但我也成功使用了相关对象。


• 为了确保窗口显示在其他所有窗口（包括系统UIAlertControllers）之上，我设置了windowLevel。 （ window.windowLevel = UIWindowLevelAlert + 1 ）

• Your UIWindow must be strongly referenced. If it's not strongly referenced it will never appear (because it is released). I recommend using a property, but I've also had success with an associated object.
• To ensure that the window appears above everything else (including system UIAlertControllers), I set the windowLevel. (window.windowLevel = UIWindowLevelAlert + 1)

最后，我有一个完成实施，如果你只是想看看。

Lastly, I have a completed implementation if you just want to look at that.

https://github.com/dbettermann/DBAlertController

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